Process Simulation and Techno-Economic Analysis of Wolffia-Integrated Recirculating Aquaculture Systems for Nutrient Recovery and CO2 Utilization

Recirculating aquaculture systems (RASs) improve water-use efficiency in fish production but generate nutrient-rich effluents requiring management. Integrating aquatic biomass cultivation into RASs offers a promising approach to nutrient recovery, CO2 utilization, and biomass production. This study evaluates the technical and economic feasibility of integrating Wolffia globosa cultivation with RASs through process simulation and techno-economic analysis (TEA). A pilot-scale system in Thailand was modeled using SuperPro Designer, comparing static and suspended aeration cultivation. The suspended configuration required only ~10–12 m2 for 28.80 m3, whereas static cultivation required 131 m2 for 32.80 m3, corresponding to about a 12-fold reduction in land area. The suspended system achieved higher annual biomass production (1056 kg dry weight (DW) yr−1) than the static system (690 kg DW yr−1), corresponding to CO2 fixation of ~1.50 and ~0.98 t CO2 yr−1, respectively. The static system achieved higher nutrient removal efficiencies (97% N and 99.66% P), while the suspended system showed lower removal (64% N and 65.30% P) but higher productivity. Economic analysis confirmed feasibility, with the suspended system achieving higher return on investment (17.56% vs. 12.89%) and a shorter payback period (5.70 vs. 7.76 years). These results demonstrate the potential of RAS–Wolffia integration as a circular approach for resource recovery and sustainable aquaculture.